The present invention relates to a hypersonic aircraft engine, more particularly such an engine capable of being operated in either a turbojet or a ramjet mode.
It is known in the art to use air-breathing turbojet engines to power aircraft to speeds approaching Mach 4 and to use ramjets to power the aircraft up to speed of Mach 7 or 8. It is also generally known to combine these engines into a single power plant to power hypersonic aircraft.
Such combined power plants have typically utilized a central air inlet duct to supply air to the turbojet engine and have utilized an annular duct enclosing the turbojet engine and/or the turbojet engine inlet duct in order to supply air to the ramjet portion of the power plant. Such designs are disclosed in U.S. Pat. Nos. 3,540,221 and 4,909,031, and have been discussed in Publication No. IAF-90-256 of the 41st Congress of the International Astronautical Federation in Dresden, Germany on Oct. 6-12, 1990.
While such power plants have proven theoretically feasible, they have suffered practical drawbacks due to their inherent complexity and the difficulties in accessing the turbojet engine for repair and/or maintenance.